Adriaan Vanheule

A European Database of Fusarium graminearum and F. culmorum Trichothecene Genotypes

Fusarium species, particularly Fusarium graminearum and F. culmorum, are the main cause of trichothecene type B contamination in cereals. Data on the distribution of Fusarium trichothecene genotypes in cereals in Europe are scattered in time and space. Furthermore, a common core set of related variables (sampling method, host cultivar, previous crop, etc.) that would allow more effective analysis of factors influencing the spatial and temporal population distribution, is lacking. Consequently, based on the available data, it is difficult to identify factors influencing chemotype distribution and spread at the European level. Here we describe the results of a collaborative integrated work which aims (1) to characterize the trichothecene genotypes of strains from three Fusarium species, collected over the period 2000–2013 and (2) to enhance the standardization of epidemiological data collection. Information on host plant, country of origin, sampling location, year of sampling and previous crop of 1147 F. graminearum, 479 F. culmorum, and 3 F. cortaderiae strains obtained from 17 European countries was compiled and a map of trichothecene type B genotype distribution was plotted for each species. All information on the strains was collected in a freely accessible and updatable database (www.catalogueeu.luxmcc.lu), which will serve as a starting point for epidemiological analysis of potential spatial and temporal trichothecene genotype shifts in Europe. The analysis of the currently available European dataset showed that in F. graminearum, the predominant genotype was 15-acetyldeoxynivalenol (15-ADON) (82.9%), followed by 3-acetyldeoxynivalenol (3-ADON) (13.6%), and nivalenol (NIV) (3.5%). In F. culmorum, the prevalent genotype was 3-ADON (59.9%), while the NIV genotype accounted for the remaining 40.1%. Both, geographical and temporal patterns of trichothecene genotypes distribution were identified.

Deoxynivalenol: A Major Player in the Multifaceted Response of Fusarium to Its Environment

The mycotoxin deoxynivalenol (DON), produced by several Fusarium spp., acts as a virulence factor and is essential for symptom development after initial wheat infection. Accumulating evidence shows that the production of this secondary metabolite can be triggered by diverse environmental and cellular signals, implying that it might have additional roles during the life cycle of the fungus. Here, we review data that position DON in the saprophytic fitness of Fusarium, in defense and in the primary C and N metabolism of the plant and the fungus. We combine the available information in speculative models on the role of DON throughout the interaction with the host, providing working hypotheses that await experimental validation. We also highlight the possible impact of control measures in the field on DON production and summarize the influence of abiotic factors during processing and storage of food and feed matrices. Altogether, we can conclude that DON is a very important compound for Fusarium to cope with a changing environment and to assure its growth, survival, and production of toxic metabolites in diverse situations.

The compositional mosaic of Fusarium species and their mycotoxins in unprocessed cereals, food and feed products in Belgium

Global food safety depends on continuous monitoring of food contaminants such as mycotoxins in cereals and cereal-derived products. Here, we combine this type of investigation with quantitative occurrence data on Fusarium infestation of these products in extensive correlation studies. Finally, this contributes to a thorough understanding of the presence, origin and physiology of Fusarium Head Blight (FHB) related mycotoxins and the correlations within their ranks. Two hundred and thirty-seven samples were analyzed from diverse cereal matrices, representing the most important stages of the cereal food and feed chain in Belgium. Food, feed and non-processed field samples were investigated, with a strong emphasis on whole-grain food products. Two approaches were pursued to estimate the full scope of FHB and its repercussions: UPLC-MS/MS was applied to detect twelve different mycotoxins, and Q-PCR was used to measure the presence of ten Fusarium species. We found that different matrices have different characteristic contamination profiles, and extensive correlation studies identified certain mycotoxins for future assessment (e.g. moniliformin produced by the Fusarium avenaceum/Fusarium tricinctum species group). The investigated harvest year of 2012 yielded many non-processed field materials containing elevated levels of deoxynivalenol (DON), while even in a so-called DON-year less prevalent toxins such as T-2 and HT-2 might be considered problematic due to their consistent co-occurrence with related mycotoxins. Our data illustrate complex interactions between the many Fusarium species that are responsible for FHB and their mycotoxins. Correlation studies demonstrate that consistent co-occurrence of mycotoxins is not to be neglected, and pinpoint issues for future surveillance and legislation.

Impact of Fungicide Timing on the Composition of the Fusarium Head Blight Disease Complex and the Presence of Deoxynivalenol (DON) in Wheat

Kris Audenaert1,2, Sofie Landschoot1,2, Adriaan Vanheule1,2, Willem Waegeman3, Bernard De Baets3 and Geert Haesaert1,2 1Associated Faculty of Applied Bioscience Engineering, Ghent University College, Ghent 2Laboratory of Phytopathology, Faculty of Bioscience Engineering, Ghent University, Ghent 3KERMIT, Department of Mathematical Modelling, Statistics and Bioinformatics, Ghent University, Ghent Belgium

Detached leaf in vitro model for masked mycotoxin biosynthesis and subsequent analysis of unknown conjugates

The manuscript details the development of an in vitro model plant system using detached leaves because there is a need for biosynthetic methods for the production and isolation of masked mycotoxins. This detached leaf in vitro model was firstly applied to deoxynivalenol with satisfying results. The biosynthesis of deoxynivalenol-3-glucoside was confirmed using its respective commercially available reference standard. Secondly, the detached leaf in vitro model was applied to T-2 toxin. Mono- and tri-glucoside derivatives of T-2 toxin and HT-2 toxin, T-2-(3)-glucoside, T-2-(3)-triglucoside and HT-2-(3)-glucoside were identified and characterised using Orbitrap high-resolution mass spectrometry. This is the first report on a triglucoside of T-2 toxin. The discovery of new masked forms implies the importance of the development of analytical methods for their detection, the constitution of toxicity studies, and proving the relevance of their presence in the food and feed chain.

Genetic divergence and chemotype diversity in the fusarium head blight pathogen Fusarium poae

Fusarium head blight is a disease caused by a complex of Fusarium species. F. poae is omnipresent throughout Europe in spite of its low virulence. In this study, we assessed a geographically diverse collection of F. poae isolates for its genetic diversity using AFLP (Amplified Fragment Length Polymorphism). Furthermore, studying the mating type locus and chromosomal insertions, we identified hallmarks of both sexual recombination and clonal spread of successful genotypes in the population. Despite the large genetic variation found, all F. poae isolates possess the nivalenol chemotype based on Tri7 sequence analysis. Nevertheless, Tri gene clusters showed two layers of genetic variability. Firstly, the Tri1 locus was highly variable with mostly synonymous mutations and mutations in introns pointing to a strong purifying selection pressure. Secondly, in a subset of isolates, the main trichothecene gene cluster was invaded by a transposable element between Tri5 and Tri6. To investigate the impact of these variations on the phenotypic chemotype, mycotoxin production was assessed on artificial medium. Complex blends of type A and type B trichothecenes were produced but neither genetic variability in the Tri genes nor variability in the genome or geography accounted for the divergence in trichothecene production. In view of its complex chemotype, it will be of utmost interest to uncover the role of trichothecenes in virulence, spread and survival of F. poae.